The aerosol fire-extinguishing techniques emerged in the 1990s are fire-extinguishing techniques that are based on the intense oxidation-reduction reaction between oxidant and fuel, and utilize the chemical reaction of the resulted active inhibiting agent to prevent combustion and chain reaction of free radical groups in the flame, so as to achieve the purpose of fire-extinguishing. The aerosol fire-extinguishing technique mainly comprises three types: hot aerosol fire-extinguishing technique, cold aerosol fire-extinguishing technique, and fine water mist fire-extinguishing technique, among which hot aerosol fire-extinguishing techniques comprise pyrotechnic compound-based hot aerosol fire-extinguishing techniques and water-based hot aerosol fire-extinguishing techniques. At present, most pyrotechnic compound-based hot aerosol fire-extinguishing techniques employ solid pyrotechnic compound extinguishing agents composed of oxidant, combustible, adhesive, and combustion rate controller. As a substitute for halon, pyrotechnic compound-based hot aerosol extinguishing agents have significant advantages over other types of extinguishing agents, for example, they have high extinguishing efficiency, the structure of fire-extinguishing equipment is simple, there is no need for pressure container, the fire-extinguishing units can be modularized and combined as required, the extinguishing agents can be stored at normal temperature and normal pressure, the fire-extinguishing equipment is easy to service and maintenance, the extinguishing agents have long shelf life and low cost, no ozone depletion potential (ODP=0), low greenhouse warning potential (GWP), and high cost/performance. These extinguishing agents are favored in the market and can drive implementation of the halon replacement program.
In the prior art, nitrate alkali salts, especially potassium nitrate, are the first choice for oxidant in most pyrotechnic compound-based hot aerosol fire-extinguishing techniques, because they can meet the most requirements of the principles for component selection. In existing techniques of fire-extinguishing aerosol composition with single-component potassium nitrate as the oxidant, the most representative hot aerosol fire-extinguishing agent techniques are those disclosed in the Russian series patent group, such as patent applications RU2230726, RU2184587, RU2214848, RU2150310, RU2108124, RU2091106, RU2076761, RU2151135, RU2116095, RU2006239, RU2022589; and patent applications in other countries, such as WO0158530, WO9733653, WO9423800, U.S. Pat. Nos. 5,831,209, 6,042,664, 6,264,772, 5,573,555, 6,116,348, etc.; what take the second position are fire-extinguishing aerosol composition techniques that employ bi-component or multi-component oxidants mainly composed of potassium nitrate and/or potassium perchlorate and/or assisted with nitrates or carbonates of other alkali metals or alkaline earth metals, as disclosed in patent applications such as CA2250325, DE19915352, UA7773, EP0561035, WO2005023370, RU2157271, RU2098156, US20020121622, U.S. Pat. Nos. 5,423,385, 5,492,180, 5,425,426, 6,277,296, etc. As for selection of combustibles, there is a wide range of substances that can meet the principle for component selection. The organic or inorganic combustibles that can meet the requirements are selected on the premise of ensuring negative oxygen balance design, such as the combustibles disclosed in patent applications RU218458, RU2214848, US20010011567, U.S. Pat. No. 6,264,772, RU2157271, RU2050878, U.S. Pat. No. 5,831,209, WO9733653, EP0561035, etc. With respect to the water-based hot aerosol fir extinguishing agent techniques, the oxidants and combustibles selected are typically composed of ammonium nitrate, ammonium perchlorate, potassium nitrate, strontium nitrate, or guanidine nitrate and like components that can generate gas, moisture content, and metal solid particles on the premise of ensuring high oxygen balance design, such as those disclosed in patent applications U.S. Pat. Nos. 6,277,296, 6,093,269, 6,045,726, 6,019,861, 5,613,562, etc.
Above patented hot aerosol fire-extinguishing techniques were fire-extinguishing products favored in recent years for their advantageous features of high extinguishing efficiency, low price, convenient maintenance, etc. However, as the market application and further development of actual products, many drawbacks of existing techniques and products described above have been discovered. Recently, a great deal of application practices and research efforts have shown: fire-extinguishing agents with single-component or multi-component oxidants mainly composed of potassium nitrate produce strongly alkaline conductive substances (e.g., potassium hydroxide) that can cause secondary damage to the space and objects to be protected, although they have high fire-extinguishing efficiency. Especially, the moisture content and metal oxides produced by water-based hot aerosol fire-extinguishing agents tend to form strongly alkaline conductive substances, which may lead to damage or erode general electric apparatuses in instrument rooms, control rooms, generator rooms, battery cabinets, communication base stations, transformer substations, etc., and thereby result in irreparable consequences, when these products are used to extinguish fire in such environments. Moreover, if the resulting nitrous oxide can't be decomposed timely, it will have toxicity to human's nerve system. In view of the problems, some research institutions and manufacturers have put forth some hot aerosol fire-extinguishing schemes that have taken both fire-extinguishing efficiency and secondary damages into consideration, such as the technical scheme of aerosol fire-extinguishing agent with strontium nitrate as the only oxidant, as disclosed in patent application CN200510105449. However, the most severe drawback of that technical scheme is: though the technical scheme reduces secondary damages to general electric apparatuses, it severely degrades the fire-extinguishing efficacy of the fire-extinguishing agent. The fire-extinguishing compositions disclosed in patent application U.S. Pat. No. 5,613,562 and U.S. Pat. No. 5,609,210 employ strontium nitrate as the oxidant, which mainly acts as a power source to gasify another fire-extinguishing liquid that contains C—F bonds and C—H—F bonds and then spurt the liquid/gas to the fire; however, the resulting hydrofluoric acid has not only high toxicity but also high corrodibility. That technique belongs to a water-based hot aerosol fire-extinguishing technique. Though the fire-extinguishing composition disclosed in patent application U.S. Pat. No. 6,019,861 contains potassium nitrate or strontium nitrate component, the potassium nitrate or strontium nitrate component is only used as an additive or a co-oxidant, and the main oxidant is ammonium nitrate that must be subjected to phase stabilization; in addition, the main purpose of the potassium nitrate or strontium nitrate component is to provide high quality dilating gas. Though the fire-extinguishing composition has an advantage of lower temperature when it is used in the fire-extinguishing technique, it degrades the combustion rate and the gas generation rate. A pyrotechnic gas generating agent with high oxygen balance is disclosed in patent application U.S. Pat. No. 6,093,269. In the pyrotechnic gas generating agent, the highly concentrated strontium nitrate is mainly used to keep neutral balance between oxygen and fuel; the pyrotechnic gas generating agent is mainly used in propelling agent compounds for automobiles, gun thrusters, expansion devices, and air bags.
Existing techniques that are close to the technical scheme of the present invention are the techniques disclosed in patent applications CN1739820A, CN1150952C, and CN1222331C, wherein, CN1150952C and CN1222331C are former patent applications of the inventor. A drawback of the two techniques disclosed in patent applications CN1150952C and CN1222331C is: in terms of balance between fire-extinguishing efficacy and corrosion to electric apparatuses, no specific design is provided for the requirements for insulation of different electric apparatuses. However, different types of electric apparatuses have different withstand capability against electrostatic accumulation or acid-alkali corrosion at different severity levels; for example, for heavy current electric apparatuses such as generators, electric motors, high voltage or low-voltage apparatuses, electric networks, and cables, the insulation resistance usually should be ≧1MΩ and <20MΩ (see the standards of electric power industry of P. R. C., such as “Code for Quality Inspection and Assessment of Electric Apparatus Installation Engineering (Inspection of Engineering Quality of Rotating Motors)” (DL/T5161.7-2002), etc.); for general electric apparatuses such as communication apparatuses, computers, onboard electric apparatuses, and electric medical apparatuses, etc., the insulation resistance usually should be ≧20MΩ and <100MΩ (see standards of electronic industry of P. R. C. and standards of communication industry of P. R. C., standards of computer industry of P. R. C., such as “General Code for Semi-Conductor Integrated Circuits” (GB6649-86), “Handbook of Surface Insulation Resistance” (IPC9201), etc.); for precision electric apparatuses such as instruments and gauges and their substrates and PCBs, the insulation resistance usually should be ≧100MΩ (see standards of electronic industry of P. R. C., international standards of printed circuit industry, such as “Handbook of Insulation Performance and Quality of Electric Apparatuses for Printed Circuit Board Assembly) (IPC-CC-8308), “Requirements for Safety of Electronic Measuring Instruments” (GB4793), and “General Specification for General-Purpose Printed Circuit Board Connectors” (GJB1717-93), etc.). Since different electric apparatuses have different requirements for insulation resistance, it is inappropriate to use a fire-extinguishing composition with the same components for different electric apparatuses in terms of fire-extinguishing efficacy and cost. Therefore, the fire-extinguishing compositions disclosed in formers patent applications of the inventor are not perfect in terms of the design of components and contents, and must be refined for some technical features and parameters. In the prior art, no special technique on fire-extinguishing aerosol composition that can prevent or reduce secondary damages to electric apparatuses while not compromising the fire-extinguishing efficacy is found, except for the techniques described above.